掺杂多元金属铁基改性生物焦的Hg^(0)脱除特性及耦合协同机理研究  

Study on the Elemental Mercury Removal Characteristics and Coupling Synergetic Mechanism of Doped Multi-metal Iron-based Modified Biochar Materials

作　　者：贾里 秦舒宁 李泽鹏 郭晋荣 张永强 张柳 樊保国[1] 金燕[1] JIA Li;QIN Shuning;LI Zepeng;GUO Jinrong;ZHANG Yongqiang;ZHANG Liu;FAN Baoguo;JIN Yan(College of Electrical and Power Engineering,Taiyuan University of Technology,Taiyuan 030024,Shanxi Province,China)

机构地区：[1]太原理工大学电气与动力工程学院,山西省太原市030024

出　　处：《中国电机工程学报》2021年第21期7378-7390,共13页Proceedings of the CSEE

基　　金：国家自然科学基金项目(U1510135,U1810126,U1910214);山西省高等学校科技创新项目(2020L0073)。

摘　　要：通过结合化学共沉淀法和溶胶凝胶法制备以生物焦为载体的铁基复合脱除剂,主要包括未掺杂其他金属的单铁基负载改性生物焦,以及基于铁基掺杂多元金属(Ce、Cu、Co、Mn)的改性生物焦。在获得改性生物焦Hg^(0)脱除特性的基础上,识别生物焦的吸附和氧化位点,对前驱体制备与生物质热解、生物焦与所负载改性物质、不同负载金属自身之间的耦合作用机理及协同作用机制进行研究,结合吸附动力学过程,利用程序升温脱附技术,揭示改性生物焦对Hg^(0)氧化和吸附过程之间的深层次差异性机理,以及Hg^(0)脱除过程的关键作用机制,研究发现:基于铁基改性条件,掺杂多元金属后所获得生物焦样品的Hg^(0)脱除性能获得了显著提升,而且掺杂双金属的改性样品的脱除性能整体优于掺杂单金属的改性样品;改性生物焦对Hg^(0)的脱除主要包括吸附和氧化过程;Hg^(0)和Hg-OM是Hg^(0)在改性生物焦表面的主要赋存形态;吸附过程分为外部和内部传质两个阶段,均为多层吸附;在吸附过程中,生物焦的微孔和较小孔径的介孔提供Hg^(0)的物理活性吸附位,表面化学官能团和晶相结构中的离子空位则为化学吸附位点;均匀分散在Fe相中的多元掺杂金属离子及对应氧化物、晶格氧、化学吸附氧以及卤素成分均为反应过程中主要的氧化位点,并形成了稳定的生物焦表面氧化体系;足够活性和数量的吸附位点利于优化吸附与氧化过程之间的主导关系;所掺杂的金属氧化物之间可以起到协同促进的作用,最终大幅提高改性生物焦的Hg^(0)脱除性能。In this paper,iron-based composite adsorbents with biochar as carrier were prepared by chemical coprecipitation method and sol-gel method,including single iron-based loaded modified biochar without doping other metals,and modified biochar based on iron-based doped multi-metal(Ce,Cu,Co,Mn).On the basis of the Hg^(0) removal characteristics of the modified biochar,the adsorption and oxidation sites were identified.The coupling and synergistic mechanism between precursor preparation and biomass pyrolysis,between the biochar and the loaded modified substances,and between the different loaded metals themselves were explored.Combined with the adsorption kinetic process,the temperature programmed desorption technology was used to reveal the deep difference mechanism between the Hg^(0) oxidation and adsorption process of modified biochar as well as the key mechanism of Hg^(0) removal process.It was found that based on the iron-based modification conditions,the mercury removal performance of the biochar samples doped with multiple metals had been significantly improved.The Hg^(0) removal performance of the modified samples doped with bimetals were overall better than those of the doped single modified samples.The removal of Hg^(0) by modified biochar mainly included adsorption and oxidation processes,HgO and Hg-OM were the main combined forms of Hg^(0) on the surface.The adsorption process was divided into two stages of external and internal mass transfer,both of which were multilayer adsorption.In the process of adsorption,the micropores and the less mesopore of biochar provided the physical active adsorption sites of Hg^(0),while the surface chemical functional groups and ion vacancies in the crystal phase structure were chemical adsorption sites.Multi-doped metal ions and the corresponding oxides uniformly dispersed in the iron phase,lattice oxygen,chemisorbed oxygen and halogen components were the main oxidation sites during the reaction process,forming a stable oxidation system on the biochar surface.Sufficient activ

关 键 词：生物焦 金属掺杂改性 Hg^(0)脱除机理 吸附/氧化位点 耦合作用机制 

分 类 号：TK09[动力工程及工程热物理]